Revert "Had to remove donet related stuff from VideoBuffer, ChunkGenerator, PlayerSimpleSkip"

This reverts commit b4dfa3cdbd9b56b0641c6e2d3ce49d32f51f1844.
Cleanup
Let peers report statistics (e.g. for missed chunks)
Extracted some functions from AppSettingsDonet to AppSettings
to get rid of the tight coupling to some classes
Minor
Added small script to create a histogram for the hopcount
Updated .gitignore
ConnectConfirm msgs also contain the next seq-number that will be sent
"on that line" (so that the child node can initialize its buffer correctly)
MultitreeStatistics collect data about missed/hit chunks
Removed a class member